First time I ran into one of these. The heater kick's on once at first start up and then nothing. There is a blue spark inside the heater relay at start up before heater kick's on. I can only assume it's a bad relay. My thinking is blue spark when contact's meet are not good

Venting is clear.

I was going to get into the manual tonight but wondered if anyone had any insight. Could the transformer be sending the wrong current to the relay or am I on the right track of my assumption of a bad relay.

Check for voltage on the low voltage end (across coil) . Coil should always have voltage as long as it is calling for heat. It was rare to see a contact go but the low voltage coils failed more frequently.

I already had the relay on order as soon as I saw that spark I figured that was it..thank you though

Maybe we should have a classified board AJ

It's an out of town call so will know not be able to check until part is in and head back out. I'm understanding the unit more now. 24 VDC on the low end and 220 VAC on the high end. Sure hope it's not the control board that's a pricey part!